| 摘要: | 本研究聚焦於臺灣西北部沿海地區，涵蓋約95公里長的海岸線與向外延伸40公里的海域（範圍為東經119.5°至121.5°、北緯23.5°至25.5°），包含紅樹林、濕地與珊瑚礁等重要生態敏感區。針對1993年至2024年間的長期觀測資料，系統性分析該區域在氣候變遷與人為開發雙重壓力下的海洋環境變化趨勢。本研究透過時間序列分析、空間分布評估及氣候模態分類，評估多種與生態系統健康密切相關的關鍵參數，包括海水表面溫度（SST）、鹽度（SSS）、表觀可見波長（AVW）、490奈米漫射衰減係數（Kd490）、葉綠素濃度（Chl-a）與海洋熱浪等級（MHW）。結果顯示，過去32年間臺灣西北部沿岸SST與海水表面高度分別以每年約0.02°C與0.03公分的速率上升，鹽度則每年下降約0.005至0.007 psu，且在太平洋十年振盪（PDO）為負值與反聖嬰（La Niña）年期間變化最為顯著，2015年前後亦為一重要轉折點。光學衛星觀測顯示，距岸約8公里處的AVW每年下降約0.01奈米，與Chl-a濃度呈負相關；而Kd490與Chl-a則分別以每年0.0008 /公尺與0.0172 mg/m³的速率上升，反映出浮游植物生產力提升與水體濁度增加，且具有顯著的時空變異特徵。在氣候模態分析中發現，PDO−與反聖嬰期間，MHW事件強度增加，且葉綠素濃度的空間異質性更為明顯，浮游植物分布受到大尺度氣候循環調控的影響更加顯著。生地化參數方面，spCO₂與fgCO₂自1993年以來分別以每年約1.80 μatm與0.02 mol C m⁻²的速率上升，顯示海水吸收大氣CO₂的能力持續增強；相對地，總鹼度（TA）與pH值則分別以每年約0.02 μmol kg⁻¹與0.002的速率下降，顯示海水中和酸化的緩衝能力逐漸減弱。此外，高空間解析度的全球變遷觀測任務–氣候任務（GCOM-C）衛星資料，進一步描繪出SST由東北向西南遞增、Chl-a濃度由近岸向外海遞減的分布特性，突顯地形效應與水團交會對沿岸浮游生態的重要控制作用。相較中解析度資料，高解析度影像顯著提升對沿岸生態與物理變化的偵測能力與監測效率，對長期海洋變遷研究具有重要意義。;This study focuses on the northwestern coastal region of Taiwan, covering approximately 95 km of coastline and extending 40 km offshore (between 119.5°–121.5°E and 23.5°–25.5°N), encompassing ecologically sensitive areas such as mangroves, wetlands, and coral reef habitats. Based on long-term datasets from 1993 to 2024, this study systematically analyzes changes in the marine environment under the dual influence of climate change and coastal development. Using time-series analysis, spatial distribution assessments, and climate regime classifications, the study evaluates key indicators of ecosystem health, including sea surface temperature (SST), sea surface salinity (SSS), apparent visible wavelength (AVW), diffuse attenuation coefficient at 490 nm (Kd490), chlorophyll-a concentration (Chl-a), and marine heatwave intensity (MHW). Results indicate that over the past 32 years, SST and sea surface height (SSH) in the region have increased at average annual rates of 0.02°C and 0.03 cm, respectively, while SSS has declined by approximately 0.005–0.007 psu per year. These changes are especially pronounced during negative phases of the Pacific Decadal Oscillation (PDO) and La Niña events, with 2015 marking a clear inflection point. Optical satellite data show that at approximately 8 km offshore, AVW has decreased by about 0.01 nm per year, inversely correlated with Chl-a. Meanwhile, Kd490 and Chl-a have increased at annual rates of 0.0008 m⁻¹ and 0.0172 mg/m³, respectively, reflecting rising phytoplankton productivity and increasing water turbidity, with substantial spatial and temporal variability. Climate mode analysis reveals that during PDO− and La Niña phases, MHW intensity increases, and Chl-a becomes more spatially heterogeneous, indicating stronger regulation of phytoplankton distribution by large-scale climate circulations. Regarding biogeochemical parameters, spCO₂ and fgCO₂ have risen since 1993 at rates of approximately 1.80 μatm and 0.02 mol C m⁻² per year, respectively, suggesting an increasing capacity of seawater to absorb atmospheric CO₂. In contrast, total alkalinity (TA) and pH have declined by about 0.02 μmol kg⁻¹ and 0.002 per year, indicating a weakening of seawater′s buffering capacity against acidification. Moreover, high-resolution satellite data from the Global Change Observation Mission–Climate reveal a distinct spatial pattern in which SST increases from northeast to southwest. At the same time, Chl-a concentrations decrease from nearshore to offshore, emphasizing the influence of topography and water mass interactions on phytoplankton distribution. Compared to medium-resolution datasets, high-resolution observations greatly enhance the detection and monitoring of ecological and physical changes along the coast, offering valuable insights for long-term marine change assessments. |
